The aims of the Neuropathology Core are: To establish a comprehensive and standardized histopathological service to research groups in the Program. ? To provide advice and expertise on neuropathological interpretation to research groups in the Program. ? To record histopathological findings and assessments in a form that is both accessible to the research groups in the Program and readily integrated with other data for the purposes of comparative analysis. ? To establish a comparative classification of human and mouse model CNS tumors. A uniform approach to histological analysis is essential to this Program. High quality methodologies and expert evaluation of preparations will enable a robust and detailed characterization of human and mouse central nervous system (CNS) tumors from across the Program. There is scope for a detailed comparative analysis at histological and molecular levels of human and mouse model CNS tumors, both within one histopathological category, e.g. primitive neuroectodermal tumors (PNETs), and across categories, e.g. PNETs versus gliomas. Histopathological analysis will be critical for validation of genetic modification in mouse model tumors, human and mouse tumor cell characterization at the immunohistochemical and molecular cytogenetic levels, and determining the effects of novel small-molecule pharmacological agents. New diagnostic approaches combining histopathological and molecular analyses will be generated by these studies, and could form the basis for patient stratification in future clinical trials of novel therapies